Technical articles

Compatibility between the US and Europe radio
frequency regions for International trade

Historically if you were not going to operate
at 125kHz, then RFID compatibility between these two regions has generally
been a mess. 125kHz was chosen by suppliers as it was below the frequency
planning of the FCC in the US and hence there were no licensing issues.
However ranges of a couple of centimeters were the best you could hope
for!

In the UHF frequency band, two divergent approaches
were being followed. In Europe generally 420 to 460MHz band was favoured
for applications involving RFID. Powers allowed were very low and each
country in the present European Union had their own plans and allocated
frequencies according to that plan. There were no allocations in the 900MHz
band and eventually GSM cell phones were allocated to this spectrum which
removed any hope of getting a 900MHz allocation.

In the US, the 400 MHz band was not favoured but
instead a wide allocation from 902-928MHz was allocated, and some other
applications even moved off this allocation, to encourage RFID development,
particulartly for monitoring movement and tolling of vehicles and railstock.
The FCC even increased the power allowable in the band to 30 watts ERP
although licensing was required.

More recently manufacturers of RFID systems have
pushed for a 13.56MHz allocation. This has been successful in Europe with
the harmonisation as part of the Unification in Europe, but still ranges
are in the 30cm region. However the FCC have also allowed this frequency,
but with such a low power that this performance is not achievable in the
US.

In the upper UHF band around the microwave oven
frequencies there is some compatibility but ranges are limited to 0.5 meters
in a passive role and technology is expensive.

Out of the harmonisation of Europe has suddenly
appeared a frequency allocation for RFID at 869MHz, a frequency that is
to be available througout the EU cutting across the former countries individual
plans. This is still some 40MHz away from that of the US but if the transponder
design has a property called "frequency agility", achieved by
having no tuned circuits and wide bandwwidth antenna, then technically
it is possible at last to have a tag that can be read in the US and EU
regions.

However all was not to be simple and the EU have
set a maximum power of only 0.5 watts ERP, only 1.6% of the power allowable
in the US. This power is so low that it is similar to that of a cell phone.

One does not know why the EU set the power so
low? As the cheapest form of tags are passive type tags, that is they have
no battery and receive their energy from the energising field and could
be made for less than US$0-20, one must assume that this type was not to
be used in Europe and instead active tags, which cost a lot more, have
batteries with limited life, and also cause ecological issues with battery
disposal were the preferred type according to their reasoning. The 0.5
watt requirement is fifty thousand times below the health reference level
so it could not have been for health reasons. Also increasing the power
allowable in a band such as used by RFID tags has only an immediate impact
on other users within a few meters of the source, as the power density
drops as the square of the distance. A person 5 meters from a 1 watt source
would experience the same power levels if they moved to 7 meters away from
a 2 watt source.

Hopefully RFID will oneday make such an impact
that EU based industry and consumers will lobby for the power levels to
be raised. This is actually a very similar situation to that of the microwave
oven which was also banned originaly in many countries due to its radio
spectrum requirements, but consumer pressure has since forced its acceptance
in the spectrum planning.

On 0.5 watt ERP a UHF tag has a range of about
30 cms.

On the 3rd May 1999, EcoTag(TM) technology arrived
in the world from Trolley Scan in South Africa to address the 0.5 watt
situation. Suddenly on 0.5 watts ERP, a passive US$0-20 tag can have an
operation range of 10 meters which must be the closest to perpetual motion
yet discovered!!!

This development has major implications for RFID
in International trade. Suddenly good reading ranges are technically achievable
in Europe. Goods made in Europe can now be labeled and read when they arrive
in the US. However non-EcoTag based labeled in the US cannot be read in
Europe and so are not useful for international trade between the regions.

Obviously US manufacturers could licence the technology
from South Africa, or would the US government put pressure on the Europeans
to raise their allowable power or face sanctions via the World Trade Organisation?